How do you become a ship's pilot?

Hi. I have a huge, intense interest in piloting water vessels. I was in the Navy for a few years, and piloted the warship I was on quite a bit. My title was the "Master Helmsman", and I piloted the ship during the most challenging and dangerous situations. Even though I'm not in the Navy anymore, my desire to pilot a ship has not depleted one bit. I don't want to rejoin the military, but I do want to know how I can become the pilot of say a cruise line, or some kind of cargo vessel. Does anyone have any information on that?